1. Field of the Invention
The present invention relates to a solid-state imaging device, and particularly, to a charge coupled device (CCD) solid-state imaging device (hereinafter referred to as a CCD imaging device), a method for manufacturing the solid-state imaging device, and a method for driving the solid-state imaging device. In addition, the invention relates to electronic apparatus using the solid-state imaging device.
2. Description of the Related Art
It is preferable that a solid-state imaging device, which is used in a digital camera module for a small-sized mobile apparatus such as a mobile phone, has a configuration appropriate for a digital camera module without a mechanical shutter.
In a progressive scan CCD imaging device, signal charges stored in a light receiving portion in all pixels are transferred to a light-shielded vertical CCD to read out one frame only with one readout operation (Japanese Unexamined Patent Application Publication No. 07-336604). On the other hand, in an interlaced scan CCD imaging device, signal charges stored in a light receiving portion of each pixel are read out in alternative manner using a vertical CCD (Japanese Unexamined Patent Application Publication No. 02-243073). In this case, signal charges, which are successively generated by photoelectric conversion in the light receiving portion of each pixel during the readout time, are inevitably added to signal charges of interest.
For that reason, in order to realize digital cameras without a mechanical shutter, it is necessary to use progressive scan CCD as a solid-state imaging device.
However, since the progressive scan CCD imaging device is necessary to have a 1-bit transferring stage of the vertical CCD for each light receiving portion, the structure of a transfer electrode in the vertical CCD becomes complicated and the amount of signal charges transferred each time in the vertical CCD is easily restricted. To the contrary, if it is assumed that the mechanical shutter is used, it is possible for the interlaced scan CCD imaging device to transfer the signal charges plural times, and therefore generally a large amount of charges generally can be treated.
On the other hand, when a CMOS type solid-state imaging device (hereinafter referred to as a CMOS imaging device) is used for a digital camera module, it is possible to perform line-ordered light reception in a light receiving portion and line-ordered readout by a transferring transistor. For this reason, it is possible to lower the influence of light successively incident on the light receiving portion by reading out signal charges in the line order in the light receiving portion as soon as a light receiving period ends.
As described above, since the signal charges are read out in the line order in the CMOS imaging device, for example, an upper line and a lower line in a screen have different light receiving time zones (timing of light receiving). If the number of pixel is large, it inevitably takes a long time to read out all screens. However, when a moving object is photographed, a blurred picture will be obtained because each line of pixels of a CMOS imaging device has different information which are captured in a different timing.
For the reasons described above, cameras mounted in mobile phones at present use the CMOS imaging device, but differences in light receiving time zones are prevented by mounting a mechanical shutter thereto. In other words, a light receiving portion in a CMOS imaging device performs the generation and accumulation of signal charges for a certain period of time when the mechanical shutter is opened, and the signal charges are read out from each light receiving portion in the line order after the mechanical shutter is closed.
As above, the Progressive scan CCD imaging device has a problem that the structure of an electrode in the CCD becomes complicated, and the CMOS imaging device has a problem that the device has to use a mechanical shutter in order to prevent differences in the light receiving time zones.